Arthropods can act as a mobile link, transporting microorganisms, like fungal spores, attached to their body (ecto-zoochory) or inside their guts (endo-zoochory) and connecting different populations or habitats1–4. This makes an understanding of the role of arthropods in our agricultural landscape even more important, because it could not only help to support farmland arthropods and species associated with them, but could also help to control crop diseases like Fusarium Head blight (FHB).
Arthropods are known to move between semi -natural and agricultural habitats and provide numerous functional links this way, e.g. like pest control5. On the one hand many of them are ground- dwelling, like the ground beetles, and so they live close to dead plant material, a known source of phytopathogenic fungi. On the other hand they can travel short distances or even longer by flying and therefore act as a potential dispersal mechanism for microscopic fungal spores. On agricultural fields, by fungi infected host plants are likely to interact with ground beetles that may substantially impact plant diseases by influencing fungi spread. Numerous ground beetles are potential vectors of FHB disease pathogens, their effectiveness might vary between species and taxa depending on their traits, like diet, morphology and habitat. Furthermore the ground beetles may also be affected by the fungi. So a wide spread FHB outbreak could alter the habitat quality and therefore the movement behavior of beetles. There is a need for an integrated approach, connecting ground beetle movement behavior and mechanisms for arthropod mediated crop disease.
For my project I will work with ground beetle species, which differ in their preferred habitat, morphology and diet. Based on that I investigate their potential as a vector for FHB causing fungal spores. The PhD project builds upon extensive previous work on carabid species occurrence and habitat use as well as on fungal disease occurrence and spatial spread, which until now have been analyzed separately from each other.
The key objectives of the PhD Project are to
(i) identify and quantity carabid movement pattern between agricultural fields and their neighboring semi -natural habitats (Cattle holes) by trapping
(ii) quantify the vector ability for different fungal spores by analyzing fungal species community associated to the carabids due to ecto- or endozoochory (Spores attached to body parts and spores that survived the digestive system of the beetle)
1. Moyo P, Allsopp E, Roets F, Mostert L, Halleen F. Arthropods Vector Grapevine Trunk Disease Pathogens. Phytopathology. 2014;104(10):1063-1069. doi:10.1094/PHYTO-11-13-0303-R
2. Drakulic J, Bruce TJA, Ray R V. Direct and host-mediated interactions between Fusarium pathogens and herbivorous arthropods in cereals. Plant Pathol. 2017;66(1):3-13. doi:10.1111/ppa.12546
3. Theron-De Bruin N, Dreyer LL, Ueckermann EA, Wingfield MJ, Roets F. Birds Mediate a Fungus-Mite Mutualism. Microb Ecol. 2018;75(4):863-874. doi:10.1007/s00248-017-1093-9
4. Kluth S, Kruess A, Tscharntke T. Insects as vectors of plant pathogens: Mutualistic and antagonistic interactions. Oecologia. 2002;133(2):193-199. doi:10.1007/s00442-002-1016-3
5. Alignier A, Raymond L, Deconchat M, et al. The effect of semi-natural habitats on aphids and their natural enemies across spatial and temporal scales. Biol Control. 2014;77:76-82. doi:10.1016/j.biocontrol.2014.06.006